| 摘要 |
PROBLEM TO BE SOLVED: To always detect an accurate image density irrespective of soiling by forming a test image in a position out of the soiled part on an image carrier having the occurrence of the soil caused by rollers different in carrying speed. SOLUTION: A region on a recording medium which is not a region where a pair of separating rollers 9 and a pair of carrying rollers 10, which are different in the carrying speed of the recording medium and adjacent to each other are in contact with each other, comes into contact with a transfer drum 5. A patch T is formed in the region on the drum 5 and the density of the patch T is read by an optical sensor 20 consisting of light emitting and receiving elements. At this time, a pair of the separating rollers 9 and a pair of the carrying rollers 10 are arranged in the center in the width direction of the carried recording medium. Therefore, a belt of soil 29 is generated in the center of the surface of the drum 5 as well. In such a case, the patch T is formed in the position out of the center of the surface of the drum 5. Moreover, the position where the patch T is formed exists within the region where a smallest size recording medium on which recording can be made by an image forming device is wound on the transfer drum 5, outside the belt 29. |
